[cups.general] file:/ Permissions

[Johannes Meixner]

Hello,

On Feb 13 20:31 Shyper wrote (shortened):
> ... create a custom backend ...

Here a very simple example for a selfmade "mylp0" backend
for the parallel port with everything hardcoded in the backend
and a possible (but unlikely) race condition:
----------------------------------------------------------------------
#! /bin/bash
# See the man page "man backend".

# debug info in /var/log/cups/error_log
set -x

# output "Device Discovery" information on stdout
if test "$#" = "0"
then
  echo 'direct mylp0:/dev/lp0 "Unknown" "lp0 device"'
  exit 0
fi

# have the input at fd0 (stdin) in any case
if test -n "$6"
then
  exec <"$6"
fi

# infinite retries to access the device
until cat /dev/null >/dev/lp0
do
  echo 'INFO: cannot access /dev/lp0 - waiting 30 seconds' 1>&2
  sleep 30
done
echo 'INFO: sending the data to /dev/lp0' 1>&2

# forward the data from stdin to the device
if cat - >/dev/lp0
then
  echo 'INFO:' 1>&2
  exit 0
else
  echo 'ERROR: failed to send the data to /dev/lp0' 1>&2
  exit 1
fi
----------------------------------------------------------------------

Place it with file name "mylp0" (i.e. what the  device discovery
information shows as URI scheme - see "man backend") in the
directory of the other backends (e.g. /usr/lib/cups/backend/)
with same owner, group and permissions as the other backends
(but a bash script needs read and exectute permissions).
Restart cupsd and verify with "lpinfo -v" that the cupsd has
recognized the new backend "mylp0".


Kind Regards
Johannes Meixner
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